In order to reduce fuel consumption modern aircraft generally fly at high altitudes of up to 15,000 m. At this altitude there is only a low air pressure of less than 120 hPa. In order to avoid impairing the comfort of the passengers during the flight, the internal pressure in the fuselage cell of the aircraft should not be lower than the ambient air pressure of around 795 hPA prevailing under normal conditions at an altitude of around 2000 m. In order to keep the internal cabin pressure in all flying conditions between the normal ambient air pressure of around 1013 hPA at sea level and the pressure of around 795 hPA prevailing at 2000 m, the fuselage cell of nearly all modern aircraft is designed to be pressure-tight.
On account of the resulting pressure difference between the ambient pressure and the internal cabin pressure the fuselage cell must absorb considerable circumferential loads. For this reason solidly designed locking systems for doors, hatches or freight doors in the fuselage cell are necessary so that the circumferential loads can be carried away via these components.
Furthermore, particularly with large hatches, doors or freight doors, beyond the secure locking, additional precautions must be taken to limit a deflection of said hatches or doors as a result of the pressure difference (so-called “deflection limiters”). An outwardly orientated deflection of hatches, doors and freight doors is undesirable amongst other things because it results in an offset in relation to the shell of the fuselage cell, whereby the aerodynamic resistance in the region of the crack of the door increases and fuel consumption rises. In addition a large deflection has a negative effect upon the sealing system.
Known embodiments of deflection limiters are generally coupled with the opening and locking system of the door, loading hatch or freight door. The deflection limiters are formed with a plurality of pins which are received so as to be displaceable in the region of the greatest deformations in the door leaf edge. Through actuation of the door locking the pins are simultaneously moved outwards and moved into or brought into engagement at least partially with recesses arranged in the region of the door jamb. Through the locking effect of the pins the deflection due to the pressure difference between the internal cabin pressure and the ambient air pressure is prevented.
The known deflection limiters require a complex and accordingly heavy mechanical lever arrangement in order to transform the movement sequences within the door locking system into a corresponding movement back and forth of the pins in the region of the deflection limiter, that is to say moving the pins into the abutment of the deflection limiter.